General Science - Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examinations.
71. What is the oscillation known as if it can be expressed in terms of single harmonic function?
[A] Harmonic oscillation
[B] Functional oscillation
[C] Regular oscillation
[D] None of the above
Show Answer
Correct Answer: A [Harmonic oscillation]
Notes:
Harmonic oscillation is that oscillation which can be expressed in terms of single harmonic function (i.e. sine or cosine function). Example :y =asin w t or y = acos w t
72. What is the S.I unit of frequency?
[A] Second
[B] Watt
[C] Hertz
[D] Joule
Show Answer
Correct Answer: C [Hertz]
Notes:
The frequency is defined as the number of periodic motions executed by body per second. The S.I unit of frequency is hertz (Hz).
73. Which of the following about S.H.M is correct?
[A] In S.H.M. acceleration is maximum at extreme position
[B] In S.H.M. velocity is minimum at extreme position
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: C [Both a and b]
Notes:
In S.H.M: 1. acceleration is maximum at extreme position. 2. velocity is minimum at extreme position. 3. Direction of velocity is either towards or away from mean position depending on the position of particle.
74. What is the oscillation in which the loss of oscillator is compensated by the supplying energy from an external source known as?
[A] Free oscillation
[B] Maintained oscillation
[C] Forced oscillation
[D] Damped oscillation
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Correct Answer: B [Maintained oscillation]
Notes:
The oscillation in which the loss of oscillator is compensated by the supplying energy from an external source are known as maintained oscillation.
75. What are those oscillations whose amplitude goes on decreasing with time are known as?
[A] Damped oscillation
[B] Maintained oscillation
[C] Free oscillation
[D] Forced oscillation
Show Answer
Correct Answer: A [Damped oscillation]
Notes:
The oscillation of a body whose amplitude goes on decreasing with time are defined as damped oscillation. In these oscillation the amplitude of oscillation decreases exponentially due to damping forces like frictional force, viscous force, hystersis etc.
76. What happens to the frequency of the pendulum if it is suspended from the ceiling of the lift moving up ward with constant acceleration?
[A] it decreases
[B] it increases
[C] may increase or decrease
[D] No change
Show Answer
Correct Answer: B [it increases]
Notes:
If the lift is moving up ward with constant acceleration a then the time period of the pendulum decreases and frequency increases.
77. What happens to the time period of the simple pendulum if the solid bob is replaced by a hollow sphere of same radius but half the mass?
[A] time period becomes double
[B] time period remains unchanged
[C] time period becomes half
[D] time period becomes four times
Show Answer
Correct Answer: B [time period remains unchanged]
Notes:
Time period of simple pendulum is independent of mass of the bob. Therefore, If the solid bob is replaced by a hollow sphere of same radius but different mass, time period remains unchanged.
78. What do we call the wave if the constituents of the medium oscillate perpendicular to the direction of wave propagation?
[A] Transverse wave
[B] Longitudinal wave
[C] Electromagnetic wave
[D] Matter wave
Show Answer
Correct Answer: A [Transverse wave]
Notes:
If the constituents of the medium oscillate perpendicular to the direction of wave propagation, we call the wave a transverse wave. If they oscillate along the direction of wave propagation, we call the wave a longitudinal wave
79. Which of the following is correct about transverse mechanical waves?
[A] they can travel through solids and gases
[B] they can travel through solids but not liquids
[C] they can travel through solids and liquids
[D] they can travel through gases but not solids
Show Answer
Correct Answer: B [they can travel through solids but not liquids]
Notes:
In transverse waves, the constituents of the medium oscillate perpendicular to wave motion subjecting each element of the medium to shearing stress. Solids and strings have shear modulus, that is they sustain shearing stress. Fluids have no shape of their own – they yield to shearing stress. This is why transverse waves are possible in solids and strings (under tension) but not in fluids.
80. For which of the following waves the Doppler effect holds true?
[A] Sound waves
[B] Electromagnetic waves
[C] Both a and b
[D] None
Show Answer
Correct Answer: C [Both a and b]
Notes:
Doppler effect is a wave phenomenon and it holds not only for sound waves but also for electromagnetic waves. When we approach a stationary source of sound with high speed, the pitch of the sound heard appears to be higher than that of the source. As the observer recedes away from the source, the observed pitch (or frequency) becomes lower than that of the source. This motion-related frequency change is called Doppler effect.
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